PROJECT SUMMARY/ABSTRACT With the increasing prevalence of obesity in the USA, diabetes mellitus is a growing concern. Most diabetic patients will die from a thrombotic vascular event (heart attack or stroke) where the effects of oxidative stress on platelets, arising from major metabolic disturbances such has hyperglycemia, play a major role. How oxidative stress directly leads to platelet dysfunction is currently an intense area of investigation. We have recently performed rigorous proteomic and metabolomic profiling in diabetic versus healthy platelets and identified specific oxidized methionine modifications in key mitochondrial metabolic proteins, that may be the source for some of the major cellular metabolic disturbances (defects in mitophagy and lipid beta- oxidation) associated with diabetic platelets. Moreover, MsrB2, an understudied mitochondrial matrix enzyme, can reverse these oxidative-stress induced methionine oxidative changes, protecting platelets. Based upon our Preliminary Studies we hypothesize that DM associated oxidative stress modifies key proteins involved in essential cellular biological and biochemical processes; mitochondria specific MsrB2 may play a critical role in reversing such potentially harmful changes, thus protecting DM patients from thrombovascular events. In addressing our hypothesis, we present three Specific Aims. Specific Aim #1 will be to assess the effects of oxidative stress on Parkin and the recently described platelet mitophagy protective process. Specific Aim #2 will be to determine whether methionine modification of HADHA, a key component of the mitochondrial trifunctional protein, perturbs mitochondrial beta-oxidation. The third Specific Aim addresses whether MsrB2 plays a role in rectifying these disturbances, in addition to possible other anti-oxidant avenues for therapy. Our team of internationally recognized experts in the areas of diabetes mellitus, platelet biology, mitochondrial biology and metabolism, will in the short term decipher important new mechanisms regulating mitochondrial dysfunction and apoptosis in diabetes mellitus. In the long term, we will have identified new targets for novel therapy against platelet mediated adverse cardiovascular events in diabetes mellitus.